Functional Assay of Voltage-Gated Sodium Channels Using Membrane Potential-Sensitive Dyes

2004 ◽  
Vol 2 (3) ◽  
pp. 260-268 ◽  
Author(s):  
John P. Felix ◽  
Brande S. Williams ◽  
Birgit T. Priest ◽  
Richard M. Brochu ◽  
Ivy E. Dick ◽  
...  
Keyword(s):  
Membrane Potential ◽  
Sodium Channels ◽  
Functional Assay ◽  
Voltage Gated ◽  
Voltage Gated Sodium Channels

scholarly journals Tracking S4 movement by gating pore currents in the bacterial sodium channel NaChBac

2014 ◽  
Vol 144 (2) ◽  
pp. 147-157 ◽  
Author(s):  
Tamer M. Gamal El-Din ◽  
Todd Scheuer ◽  
William A. Catterall
Keyword(s):  
Membrane Potential ◽  
Sodium Channel ◽  
Sodium Channels ◽  
Voltage Dependence ◽  
Periodic Paralysis ◽  
Membrane Potentials ◽  
Structural Basis ◽  
Voltage Gated ◽  
Voltage Gated Sodium Channels ◽  
Gating Charges

Voltage-gated sodium channels mediate the initiation and propagation of action potentials in excitable cells. Transmembrane segment S4 of voltage-gated sodium channels resides in a gating pore where it senses the membrane potential and controls channel gating. Substitution of individual S4 arginine gating charges (R1–R3) with smaller amino acids allows ionic currents to flow through the mutant gating pore, and these gating pore currents are pathogenic in some skeletal muscle periodic paralysis syndromes. The voltage dependence of gating pore currents provides information about the transmembrane position of the gating charges as S4 moves in response to membrane potential. Here we studied gating pore current in mutants of the homotetrameric bacterial sodium channel NaChBac in which individual arginine gating charges were replaced by cysteine. Gating pore current was observed for each mutant channel, but with different voltage-dependent properties. Mutating the first (R1C) or second (R2C) arginine to cysteine resulted in gating pore current at hyperpolarized membrane potentials, where the channels are in resting states, but not at depolarized potentials, where the channels are activated. Conversely, the R3C gating pore is closed at hyperpolarized membrane potentials and opens with channel activation. Negative conditioning pulses revealed time-dependent deactivation of the R3C gating pore at the most hyperpolarized potentials. Our results show sequential voltage dependence of activation of gating pore current from R1 to R3 and support stepwise outward movement of the substituted cysteines through the narrow portion of the gating pore that is sealed by the arginine side chains in the wild-type channel. This pattern of voltage dependence of gating pore current is consistent with a sliding movement of the S4 helix through the gating pore. Through comparison with high-resolution models of the voltage sensor of bacterial sodium channels, these results shed light on the structural basis for pathogenic gating pore currents in periodic paralysis syndromes.

scholarly journals Erratum to: Voltage-gated Sodium Channels and Blockers: An Overview and Where Will They Go?

2020 ◽  
Author(s):  
Zhi-mei Li ◽  
Li-xia Chen ◽  
Hua Li
Keyword(s):  
Open Access ◽  
Sodium Channels ◽  
Voltage Gated ◽  
Internet Portal ◽  
Creative Commons ◽  
Link Type ◽  
Voltage Gated Sodium Channels

The article “Voltage-gated Sodium Channels and Blockers: An Overview and Where Will They Go?”, written by Zhi-mei LI, Li-xia CHEN, Hua LI, was originally published electronically on the publisher’s internet portal on December 2019 without open access. With the author(s)’ decision to opt for Open Choice, the copyright of the article is changed to © The Author(s) 2020 and the article is forthwith distributed under a Creative Commons Attribution 4.0 International License (https://creativecommons.org/licenses/by/4.0/), which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.The original article has been corrected.Corresponding authors: Li-xia CHEN, Hua LI

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